The invention concerns a method for optimizing the efficiency of a set of machines comprising a turbine and a generator, wherein the method involves determining a correlation between the efficiency, flow, variable height of fall, the gate opening .DELTA..gamma. and runner opening .phi. on a model set of machines by test series, which determination yields a model optimum curve for the respective height of fall, the model optimum curve having the optimum gate opening as a function of flow and runner opening, and wherein the optimum efficiency for an operating point of a large-scale system can then be determined. A so-called double-controlled turbine is concerned here. This means that the efficiency is optimized by adjusting the gate opening .DELTA..gamma. and at the same time the runner opening .phi..
The efficiency, as generally known, derives from the ratio between the electrical output delivered by the generator to the hydraulic power input. The electrical power delivered at the generator terminals can be measured in a relatively simple fashion. On the other hand, especially with large-scale systems, determining the hydraulic energy input is very expensive, since to that end the flow needs to be measured in some way. This process has been known for a long time and has been described, e.g., in the trade magazine "Die Wasserwirtschaft," vol 1954, No. 4, pp 104-105, in the article "Simplified Process for Adjusting Kaplan Turbines to Best Efficiency."
In practice, the optimum efficiency curve is determined on a model set of machines, which in the case of large-scale turbines is built prior to constructing the large-scale system. For that purpose, an optimum efficiency curve for various heights of fall is prepared first for the model set of machines. The procedure is as follows. The runner opening .phi. is kept constant at one and the same height of fall while the gate opening .DELTA..gamma. is varied. Obtained thereby is a number of steeply rising individual curves of constant runner opening .phi.. The efficiency is determined simultaneously. The result is a statement expressing for which gate opening .DELTA..gamma., at a specific runner opening .phi., the efficiency reaches a maximum value. The result is the so-called optimum .DELTA..gamma./.phi. correlation in the form of a group of curves of optimum gate opening over the runner opening with the height of fall as a parameter which in the turbine controller represents the basis for adjustment of the turbine openings.
In practice, however, a deviation is encountered between the performance of the model set of machines and that of the large-scale system. For this reason, it is necessary to effect an adaptation on the large-scale system. Thus, while basing on the curves of the model set of machines, an optimization is carried out for the large-scale system with the aid of so-called index measurements. This optimization is unwieldy, time-consuming and expensive, since it inevitably requires a flow measurement.
The problem underlying the invention is to fashion the optimization of the curves of the optimum .DELTA..gamma./.phi. correlation obtained on the model set of machines such that it can be performed in a faster, simpler and less expensive manner than before.